Properties of aluminized steel

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This post was last edited by Black gold on 2010-8-10 at 15:58. Aluminum infiltration is a type of chemical heat treatment for metal surfaces; it involves heating steel or another material to a certain temperature so that aluminum atoms can penetrate and diffuse into the steel matrix. Depending on the specific application requirements, aluminizing can be carried out on carbon steel, low-alloy steel, and high-chromium-nickel alloy steels. After aluminum infiltration, a ferroaluminum alloy layer with special properties is formed on the surface of these materials, thereby improving their resistance to high-temperature oxidation and corrosion. It possesses excellent corrosion resistance. When the aluminum content in the aluminum-coated layer on the surface of carbon steel is greater than 15% (by weight), and under conditions of temperatures above 240°C, sulfur content greater than 0.5%, or an acid value greater than 0.5 mgKOH/g, its corrosion resistance is more than three times that of ordinary 18-8 grade stainless steel under the same conditions. Its corrosion resistance makes it suitable as a substitute for 316L, especially in environments where H2S and RCOOH (naphthenic acid) act together to cause corrosion; in such cases, the corrosion resistance of aluminum-coated steel is unsurpassed. In various corrosion media dominated by hydrogen sulfide at temperatures below 120°C, such as H2S-NH3-H2O, HCN-H2S-H2O, CO2-H2S-H2O, RNH2-CO2-H2S-H2O, and H2S-H2O, aluminized steel also outperforms chromium steel, chromomolybdenum steel, and austenitic stainless steel. Moreover, aluminized steel does not suffer from problems such as stress corrosion, intergranular corrosion cracking, or hydrogen embrittlement